The present invention relates to a keyboard unit control system and, more particularly, to an improvement in a scanning mechanism of a keyboard with a scanning matrix by means of software.
There are generally two scanning systems of the keyboard with a matrix: a software supervising/scanning system and a hardware scanning system. In the software supervising/scanning system, the amount of hardware required is relatively small. However, the scanning operation must be always supervised, resulting in a heavy load on the software. If parallel operations such as arithmetic operations are required, they may not be satisfactorily performed. Meanwhile, in the hardware scanning system, simple software can be used, but the system itself becomes large in size, resulting in high cost. Further, the software and hardware scanning systems described above are of a dynamic scanning type, so that noise may be generated. A radio wave shield must be arranged to shield noise, resulting in a higher cost. Further, if a number of keys are arranged in the keyboard unit, the mechanism becomes bulky and an LSI device suitable to control such a keyboard unit has not been developed.